remove twitter from social media definitions

Signed-off-by: Chad Dougherty <[email protected]>

Author: crd477

_config.yml

@@ -30,7 +30,6 @@ hero_line_one: The United States Research Software Engineer Association
 hero_line_two: A community of people who make research software happen.
 
 # social media
-twitter: us_rse
 bluesky: us-rse.bsky.social
 github_org: USRSE
 github_repo: usrse.github.io